I’m no Pinterest expert but I’ve managed over the last 8 months to grow my account to 2.7M viewers with 127K engaged. In the first two months I tried f/u and realized very quickly that it was hurting my reach and so I quit bothering with f/u all together. Instead I just follow back when people follow me and even then not everyone. With 127K engaged monthly viewers, I don’t really care about the fact that I have less than 3K followers.
The only tool I’ve used is Tailwind and I can honestly say that I don’t get much value out of the Tribe function.